1. Field of the Invention
This invention relates to automatic exposure control apparatus for single lens reflex cameras of the type in which the light metering is effected with the full-size aperture of the objective lens, and, more particularly, to an automatic exposure control apparatus having a digital-to-analog converter as a memory means in combination with first and second comparator for controlling the diaphragm of the camera in accordance with the preselected shutter time and the exposure value.
2. Description of the Prior Art
The prior art provides an automatic exposure control apparatus for a single lens reflex camera of the type described in which information representative of a preselected shutter time is combined with information representative of the level of brightness of a scene being photographed by a computer an output is produced which is utilized in adjusting the position of the diaphragm presetting ring, and, thereafter, the diaphragm means is driven for engagement with the presetting ring. In this manner an effective exposure aperture is automatically established in the diaphragm means. In photographic applications requiring highly accurate and reliable automatic exposure control, for example, snap-photography, however, it is desirable to eliminate or minimize the time lag existing between the adjustment of the diaphragm presetting ring and the actuation of the diaphragm driving means.
Accordingly an object of the present invention is to provide an improved automatic exposure control apparatus for a single lens reflex camera of the type described.
Another object of the invention is to provide an automatic exposure control apparatus constructed with the use of a digital-to-analog converter in combination with two comparators for permitting simultaneous actuation of the diaphragm control means and diaphragm drive means to minimize the time interval between the release of the camera and the actuation of the shutter thereof.
Still another object of the invention is to provide an automatic exposure control apparatus from which a design flexibility is derivable for facilitating the realization of broadened photographic capabilities.
Another object of the invention is to provide an automatic exposure control apparatus for a camera of the type described and having a shutter preselection exposure range and a diaphragm preselection exposure range.
Other objects and features of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings in which: